Texas Tech University researchers analyzed plastic “bumpers” - tools used to teach dogs how to fetch - and found that they contained relatively high levels of bisphenol A (BPA) and phthalates.

The two chemicals have been suspected of posing a health risk to humans because they “are known endocrine disruptors that mimic estrogen or act as anti-androgens,” according to Science Daily.

Researchers Kimberly Wooten and Phil Smith measured the bumpers’ chemical content as well as that of certain plastic chew toys by creating a substance similar to dog saliva. They then squeezed the chew toys and bumpers with metal salad tongs to mimic chewing, according to Science Daily.

Their study revealed that the bumpers contained “the high end of what you might find in children’s toys,” Wooten said. The plastic chew toys they analyzed also contained the chemicals, although at lower concentrations than the bumpers, Science Daily reported.

In addition, the researchers weathered some toys and bumpers outdoors to test whether the weathering induced the plastic products to emit more chemicals. It turns out that weathering did increase chemical output.

Now that Wooten and Smith have shown that bumpers and some plastic dog toys contain potentially harmful chemicals, they said they still have more questions that need answers.

For one, they would like to know how much of the chemicals are introduced to the dogs’ bodies while they chew on the products. They also said there currently is not a lot of data to demonstrate how BPA and phthalates affect dogs over a long period of time.

“The whole end goal was to answer the questions, ‘What does this mean for my pet? Is this a concern for our health?” Wooten told the media. “We don’t have a good answer yet because there’s no good data to compare to our findings.”